Don't know about the price but quality is better. Years ago I used some thin cheap poor quality coax cables on my subwoofer and suffered heaps of hum. Changed to thicker higher quality and the hum disappeared.

To be fair, the characteristic impedance of the cable is of very little concern... instead, you should be looking for decent shielding. Especially if you're looking to run a cable for 3-4 meters, or even longer.I've seen systems where people have used cheap cables and had a buzzing sub, as well as hum from systems where two cables have been joint (male to female connectors)... all of which has been fixed with a $60 off the shelf cable. Could they have gone cheaper? Maybe... but the buzzing of a sub is VERY annoying.

richms: Subs still insist on using stupid unballanced RCA cables, and you are connecting something which is normally earthed into a whole lot of stuff that is usually earthed and on a different power circuit.

Not had the hum get solved with a fancier cable, but have chucked a cheap car audio isolator on the RCA cable to get rid of most hum.

I have a good sub, and a good quality shielded cable, but still have that hum, can give give me more detail on what you put on ? the Car Audio isolator ?

I didnt have to earth it at all to get any benifit from it. I think that will just be earthing the core of the transfromer or have a screen between the 2 windings to stop capacitivly coupled crap making it thru.